This invention relates to the storage and protection of microcentrifuge tubes containing biological specimens such as heat-sensitive biologicals, enzymes, and the like; and more particularly this invention relates to a portable storage box of the type described which operates to maintain the contents of such tubes in an extremely cold ambient.
When not in use, it is essential that restriction enzymes and other heat sensitive biological specimens be stored in a freezer, or the like, so that they will remain dormant until used. Typically the freezers maintain the tubes, which contain such enzymes and heat labile biologicals, at temperatures ranging between 0.degree. C. and -30.degree. C. When they are to be used, a researcher usually removes a group of such tubes and their frozen contents from the freezer and places them at a convenient location on a bench top, where the tubes may remain for several hours at a time. During such intervals it is essential that the contents of the tubes, which often cost several hundred dollars per milliliter of volume, be maintained in their frozen or nearly frozen form until placed in use.
There are a number of disadvantages associated with known cold storage devices for such specimens. For example, most researchers store their restriction enzymes and heat sensitive biologicals in frost free freezers, despite the fact that such freezers have a heating cycle which operates to drive out condensation and to prevent frost. Consequently, biological specimens stored in those types of freezers may experience a fluctuating temperature profile, and as a consequence the specimens stored therein may be harmed by such fluctuations. Likewise, in the event of a power loss or "brown-out" event, the stored materials could be damaged as a result of the temporary failure of the freezer.
As for bench top ambients, enzymes and biological specimens of the type described are even more likely to be subjected to undesirable temperature fluctuations, unless extreme care is taken to maintain the unused materials consistently in a near frozen form. Although ice and dry ice devices have been suggested for bench top usage, they have proved to be rather ineffective. This is particularly true in those instances where it may be necessary to transport frozen specimens to one location or another, during which transfer the associated microcentrifuge tubes will be subjected to extreme temperature variations.
It is an object of this invention, therefore, to provide a portable, cryogenic storage box for removably supporting and maintaining enzyme-containing tubes and the like in an extremely cold atmosphere for prolonged periods of time.
Still another object of this invention is to provide a portable storage box of the type which is particularly suited for maintaining enzymes and heat sensitive biologicals in a frozen or near frozen ambient, whether in a freezer, on a bench top, or in transit from one locale to another.
A more specific object of this invention is to provide a portable, cryogenic storage box which is designed removably to support a plurality of microcentrifuge tubes in contoured openings that extend into and are surrounded by cold pack materials, which upon being frozen retain the box contents in an extremely cold temperature for prolonged periods of time.
Other objects of the invention will be apparent thereinafter from the specification and from the recital of the appended claims, particularly when read in conjunction with the accompanying drawings.